This project is part of a continuing program to develop and use bioaffinity chromatography to determine quantitative characteristics of macromolecule-involved interactions. A set of studies was completed on the interaction of nucleotide substrates and inhibitors with bovine pancreatic ribonuclease and with some semisynthetic analogues of this enzyme. In a major new project of the past year, work has progressed to its final stages on a study of the quantitative expression of antibody polyvalency in antigen binding. A study also was initiated to use quantitative affinity chromatography to characterize the interaction of psychoactive drugs with the multisubunit enzyme, bovine glutamate dehydrogenase. Finally, a separate project to investigate the use of affinity chromatography to measure rate constants for association and dissociation of ligands is still in progress.